The pandoc-types package

Text.Pandoc.Definition defines the Pandoc data
structure, which is used by pandoc to represent
structured documents. This module used to live
in the pandoc package, but starting with pandoc 1.7, it
has been split off, so that other packages can use it
without drawing in all of pandoc's dependencies, and
pandoc itself can depend on packages (like citeproc-hs)
that use them.

Text.Pandoc.Builder provides functions for building
up Pandoc structures programmatically.